81256890 has 192 divisors, whose sum is σ = 242860032. Its totient is φ = 17222400.

The previous prime is 81256883. The next prime is 81256909. The reversal of 81256890 is 9865218.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1728847 + ... + 1728893.

It is an arithmetic number, because the mean of its divisors is an integer number (1264896).

Almost surely, 2^81256890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81256890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121430016).

81256890 is an abundant number, since it is smaller than the sum of its proper divisors (161603142).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81256890 is a wasteful number, since it uses less digits than its factorization.

81256890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 112 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 39.

The square root of 81256890 is about 9014.2603689931. The cubic root of 81256890 is about 433.1317951704.

The spelling of 81256890 in words is "eighty-one million, two hundred fifty-six thousand, eight hundred ninety".